Engineering topics

Denes, Peter

Publications and source records attributed to Denes, Peter.

5 records

DOE OSTI2024

The 4D Camera: An 87 kHz Direct Electron Detector for Scanning/Transmission Electron Microscopy

We describe the development, operation, and application of the 4D Camera—a 576 by 576 pixel active pixel sensor for scanning/transmission electron microscopy which operates at 87,000 Hz. The detector generates data at ~480 Gbit/s which is captured by dedicated receiver computers with a parallelized software infrastructure that has been implemented to process the resulting 10–700 Gigabyte-sized raw datasets. The back illuminated detector provides the ability to detect single electron events at accelerating voltages from 30 to 300 kV. Through electron counting, the resulting sparse data sets are reduced in size by 10--300× compared to the raw data, and open-source sparsity-based processing algorithms offer rapid data analysis. The high frame rate allows for large and complex scanning diffraction experiments to be accomplished with typical scanning transmission electron microscopy scanning parameters.

47 OTHER INSTRUMENTATION↗

DOE OSTI2024

A Modular 512-Channel Neural Signal Acquisition ASIC for High-Density 4096 Channel Electrophysiology

The complexity of information processing in the brain requires the development of technologies that can provide spatial and temporal resolution by means of dense electrode arrays paired with high-channel-count signal acquisition electronics. In this work, we present an ultra-low noise modular 512-channel neural recording circuit that is scalable to up to 4096 simultaneously recording channels. The neural readout application-specific integrated circuit (ASIC) uses a dense 8.2 mm × 6.8 mm 2D layout to enable high-channel count, creating an ultra-light 350 mg flexible module. The module can be deployed on headstages for small animals like rodents and songbirds, and it can be integrated with a variety of electrode arrays. The chip was fabricated in a TSMC 0.18 µm 1.8 V CMOS technology and dissipates a total of 125 mW. Each DC-coupled channel features a gain and bandwidth programmable analog front-end along with 14 b analog-to-digital conversion at speeds up to 30 kS/s. Additionally, each front-end includes programmable electrode plating and electrode impedance measurement capability. We present both standalone and in vivo measurements results, demonstrating the readout of spikes and field potentials that are modulated by a sensory input.

47 OTHER INSTRUMENTATION↗

DOE OSTI2023

A low noise CMOS camera system for 2D resonant inelastic soft X-ray scattering

Resonant Inelastic X-ray Scattering (RIXS) is a powerful spectroscopic technique to study quantum properties of materials in the bulk. A novel variant of RIXS, called 2D RIXS, enables concurrent measurement of the scattered X-ray spectrum for a wide range of input energies, improving on the typically low throughput of 1D RIXS. In the soft X-ray domain, 2D RIXS demands an X-ray camera system with small pixels, large area, high quantum efficiency and low noise to limit the false detection rate in long duration exposures. We designed and implemented a 7.5 Megapixel back-illuminated CMOS detector with 5 μm pixels and high quantum efficiency in the 200–1,000 eV X-ray energy range for the QERLIN 2D RIXS spectrometer at the Advanced Light Source. The QERLIN beamline and detector are currently in commissioning. The camera noise from in-situ 3 s long dark exposures is 7e - or less and the leakage current is 6.5 × 10 -3 e - /(pixel ∙ s). For individual 500 eV X-rays, the expected efficiency is greater than 75% and the false detection rate is ~1 × 10 -5 per pixel.

47 OTHER INSTRUMENTATION↗

DOE OSTI2023

VeryFastCCD: a high frame rate soft X-ray detector

Direct X-ray detection in silicon has been transformative for scattering experiments in biology and materials science. While bump-bonded hybrid pixels have been attractive for hard X-ray detection, the challenge for single photon soft X-ray detection is sufficiently low noise. CCD structures on thick, high-resistivity silicon have been successfully used as sensors over the range of soft to hard X-rays at storage rings and FELs. The VeryFastCCD is a high frame rate, column-parallel CCD sensor with 48 μm pixels. Combined with 256-channel custom readout ASICs, frame rates of 5–10 kHz have been achieved with readout noise as low as 20 e and full-well capacity >4 × 10 5 e/pixel. Thin (10 nm and 100 nm) entrance window contact processes have also been developed which provide >85% quantum efficiency for 285 eV X-rays. Systems are currently being developed for several beamlines at the upgraded Advanced Light Source.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2023

Design of Electrostatic Aberration Correctors for Scanning Transmission Electron Microscopy

Abstract In a scanning transmission electron microscope (STEM), producing a high-resolution image generally requires an electron beam focused to the smallest point possible. However, the magnetic lenses used to focus the beam are unavoidably imperfect, introducing aberrations that limit resolution. Modern STEMs overcome this by using hardware aberration correctors comprised of many multipole elements, but these devices are complex, expensive, and can be difficult to tune. We demonstrate a design for an electrostatic phase plate that can act as an aberration corrector. The corrector is comprised of annular segments, each of which is an independent two-terminal device that can apply a constant or ramped phase shift to a portion of the electron beam. We show the improvement in image resolution using an electrostatic corrector. Engineering criteria impose that much of the beam within the probe-forming aperture be blocked by support bars, leading to large probe tails for the corrected probe that sample the specimen beyond the central lobe. We also show how this device can be used to create other STEM beam profiles such as vortex beams and probes with a high degree of phase diversity, which improve information transfer in ptychographic reconstructions.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗